before和after伪类实现四角边框

HTML+CSS

利用伪类制作边框

HTML：

  <div class="colume">
    <div class="panel bar">
      <h2>柱形图</h2>
      <div class="chart"></div>
      <div class="panel-footer"></div>
    </div>
  </div>

CSS:

.mainbox .panel {
  position: relative;
  height: 3.875rem;
  padding: 0 0.1875rem 0.5rem;
  border: 1px solid rgba(25, 186, 139, 0.17);
  background: url(../images/line.png) rgba(225, 225, 225, 0.03);
  margin-bottom: 0.1875rem;
}
.mainbox .panel::before {
  position: absolute;
  top: 0px;
  left: 0px;
   10px;
  height: 10px;
  border-left: 2px solid #02a6b5;
  border-top: 2px solid #02a6b5;
  content: "";
}
.mainbox .panel::after {
  position: absolute;
  top: 0px;
  right: 0px;
   10px;
  height: 10px;
  border-right: 2px solid #02a6b5;
  border-top: 2px solid #02a6b5;
  content: "";
}
.mainbox .panel .panel-footer {
  position: absolute;
  bottom: 0px;
  left: 0px;
   100%;
}
.mainbox .panel .panel-footer::before {
  position: absolute;
  bottom: 0px;
  right: 0px;
   10px;
  height: 10px;
  border-right: 2px solid #02a6b5;
  border-bottom: 2px solid #02a6b5;
  content: "";
}
.mainbox .panel .panel-footer::after {
  position: absolute;
  bottom: 0px;
  left: 0px;
   10px;
  height: 10px;
  border-left: 2px solid #02a6b5;
  border-bottom: 2px solid #02a6b5;
  content: "";
}